1. Field of the Invention
The present invention relates to a bonded tungsten carbide-based super hard alloy assembly and a process for producing the same. More specifically, the invention relates to a bonded tungsten carbide-based super hard alloy assembly having high bonding strength and excellent mechanical properties and a process for producing the same.
2. Description of Related Art
Bonded assemblies of a tungsten carbide-based super hard alloy and a stainless steel have conventionally been used for dies for forming a ceramic honeycomb body (honeycomb body forming dies), precision molds, dies, plugs, and the like.
As honeycomb body forming dies, those produced using the following process can be given as an example (refer to, for example, Patent Document 1). First, a plurality of back holes is formed in a first plate-shaped member so that they are opened on at least one surface side thereof. The other surface side of the first plate-shaped member and a second plate-shaped member are bonded to each other by hot pressing while inserting therebetween copper or the like as a brazing filler metal. Then, slits are formed in the second plate-shaped member in lattice form so as to be associated with the back holes formed in the first plate-shaped member. A honeycomb body forming die is thus obtained. The back holes are usually provided at a position corresponding to (overlapping with) an intersection of the lattice of the slits formed in lattice form. When a honeycomb body is obtained using the ceramic honeycomb body forming die as described in Patent Document 1, honeycomb body forming raw materials containing ceramic raw materials are introduced from the back holes. The honeycomb body forming raw materials are transferred from the back holes having a relatively large inner diameter to the narrow slits and extruded as a formed body with a honeycomb structure from the opening portion of the slits. Thus, the slit portions of the second plate-shaped member are narrow and a high pressure is applied thereto during passage of the honeycomb body forming raw materials so that they are likely to be worn. In the honeycomb body forming die as described in Patent Document 1, therefore, the second plate-shaped member is made of a tungsten carbide-based super hard alloy with high abrasion resistance. The first plate-shaped member is not required to have abrasion resistance as high as the second plate-shaped member so that it is made of a stainless steel. The honeycomb body is fired into a honeycomb structure and the fired one is used as a filter, catalyst carrier, or the like for purifying an exhaust gas of automobiles, and the like.